1. Field of the Invention
The present invention relates to an aluminum nitride sintered body and a method of manufacturing the same.
2. Description of the Related Art
As is conventionally known, when an aluminum nitride sintered body is polished, a degree of flatness in the order of several tens of nanometers is difficult to obtain. The present inventors thought that the flatness was difficult to obtain because aluminum nitride grains fall off during polishing. As a result of intensive researches, as disclosed in Japanese Patent Application Laid-open No. 2005-029458, they have found that fall-off of aluminum nitride grains can be suppressed by increasing the strength of a grain boundary and reducing the diameter of the aluminum nitride grains. In addition, the inventors have found that the strength of the grain boundary can be improved by adding SiO2 to an aluminum nitride sintered body, as disclosed in Japanese Patent Application Laid-Open No. 2005-029458.
However, when SiO2 was added to an aluminum nitride sintered body, the diameters of aluminum nitride grains are likely to increase. Therefore, improvements of grain-boundary strength and reduction of aluminum nitride grains in size are not achieved at the same time. Furthermore, when an amount of an sintering additives such as SiO2 is large, a grain boundary phase is generated. Since aluminum nitride grains and the grain boundary phase are ground at different rates, dimples are formed at the grain boundary phase. For this reason, the flatness could not be improved. Under these technical circumstances, it has been desired to provide an aluminum nitride sintered body excellent in flatness, that is, having a degree of flatness in the order of several tens of nanometers, by polishing.
The present invention has been achieved in order to solve the aforementioned problem, and an object of the invention is to provide an aluminum nitride sintered body excellent in flatness by polishing, a method of manufacturing the aluminum nitride sintered body, and a member.